Combined telephony and telegraphy



(NoModelJ J. H. ROBERTSON.

COMBINED TELEPHONY AND T-ELEGRAPHY. No. 403,292. PatentedMay 14, 1889.

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UNITED STATES PATENT OFFICE.

JAMES H. ROBERTSON, OF RUTHERFORD, NEW JERSEY.

COMBINED TELEPHONY AND TELEGRAPHY.

SPECIFICATION forming part Of Letters Patent No. 403,292, dated May 14, 1889.

' Application filed January 6, 1887. Serial No. 223,537. (No model.)

To all whom it may concern:

Be it known that 1, JAMES H. ROBERTSON, a citizen of the United States, residing in Rutherford, Bergen county, New Jersey, have invented a new and useful Improvement in Combined Telephony and Telegraphy, of which the following is a specification.

The object of my invention is to utilize the circuit of my autographic telegraph (for which an application was filed by me in the United States Patent Office June 30, 1886, Serial N 0. 206,692) for telephonic purposes in such manner that both the telegraphic and the telephonic instruments can be used simultaneously without interference with each other. I accomplish this object by the means hereinafter described and claimed.

The accompanying drawing, forming part of this specification, illustrates a combination of parts embodying my invention. In said drawing I have shown two line-wires connecting the autographic instruments of separate stations; but, if desired, only one line-wire may be used, as described, for example, in application of E. A. Cowper, filed August 7, 1886, Serial No. 210,467.

My present invention is adapted to both arrangements, though the one illustrated is preferred.

Referring to the drawing, 1 and 2 designate the line-wires, in which the transmitters 3 and receivers 4 of the autographic telegraph are inserted. The transmitters consist, in part, of piles of carbon disks, as fully described in the application hereinbefore referred to, and the receivers may be also of the construction therein shown or of any other suitable construction. The two line-wires are connected at each end to a single ground-wire, 5, and the batteries 6 and 7 are of equal strength, and have their like poles opposed to each other, as fully described in the application hereinbefore referred to.

I combine the telephonic apparatus with the telegraphic circuit in the following manner: I wind the secondary wire 8 of the inductioncoil 9 around both the electromagnets of the telegraphic receiver 4. In said secondary circuit is placed the telephonic receiver 10, the

transmitter 11 and battery 12 being located in the primary circuit 13, as usual. It is not essential that the secondary wire 8 be wound around both electro-magnets, for it may be wound around only one of them, though better results are attained when wound around both, as shown.

As in using the autographic telegraph, the circuit is never broken, but merely increased or decreased in resistance, thus decreasing or increasing the strength of the current, it is clear that there is at all times an unbroken circuit for an induced current of electricity. This induced current will pass through the transmitters and receivers of the autographic telegraph without affecting them-c. (2., without interfering with the battery-currents. It will also be observed that any changes which take place in the strength of the current flowing in the line, due to the operation of the telegraphic instruments, cannot in the least affect the telephonic instruments, for the reason that such changes are made gradually.

At 14 I have shown a switch which is preferably closed, for evident reasons, when writing is not being done. I have shown switches in only one line; but they are preferably used in both.

It will be apparent, without further explanation, that the autographic telegraph and the telephone may be used simultaneously on the same line wire or wires without any interference with each other, for the reasons hereinbefore stated.

Having thus described my invention, what I claim, and desire to secure by United States Letters Patent, is

The combination, with an autographic telegraph, of a telephone the secondary circuit of which is arranged in inductive proximity to the receiver electro magnets of the autographic telegraph, substantially as described.

In testimony whereof I have hereunto subscribed my name.

JAMES H. ROBERTSON. 

